Electric furnace



L. J. HANCOCK ET AL Mar. 3, 1925.

ELECTRIC FURNACE Filed Sept. 11, 1922 /NVENTO/?S.-

THOMAS E. HAA/QocK.

Patented Mar. 3, 192$;c

UNITED STATES PATENT orsrcs.

LESLIE JOEN HANCOCK AND THOMAS REGINALD HANCOCK, OF WALLINGTON, ENG-LAND, ASSIGNORS TO OSCAR VIVIAN ASSER, OF LONDON, ENGLAND.

ELECTRIC FURNACE.

Application filed September 11, 1922. Serial No. 587,442.

To all whom it may concern."

Be it known that we, LEsLIn JOHN HAN- COCK and THOMAS REGINALD HANCOCK.of Melbourne. Works, W'allington, in the county of Surrey, England,British subjects, have invented certain new' and useful Improvements inElectric Furnaces, ,of which the following is a specification.

This invention has for its object to H) cheapen and simplify theconstruction of electric furnaces by obviating the use of the wireelectrical resistance coils generally employed in such apparatus.

According to this invention a series of W longitudinally disposed rodsof carbon or graphite surrounds a tube of refractory material, theinterior of which constitutes the heating space, said rods beingsuitably connected together in any required order at their ends andbeing preferably insulated from one another and from said tube byrefractory material of high melting point such as alundurn. Preferablythe tubular coreand its surrounding rods and insulation are enclosedwithin a chamber packed .with magnesia, kieselguhr or like nonconductor.

In one form of the invention the carbon or graphite rods are disposed ina circular series of longitudinally extending apertures formed in thewall of a tube of alundum, said apertured tube being shorter in lengththan the tube which constitutes the heating chamber but being adapted tofit thereover. If desired the carbon rods maybe protected from oxidationby treating them in any well known manner.

The invention will be described with reference to the accompanyingdrawings of which Figure 1 is a longitudinal sectional elevation 'on'the line 1-1 of Figure 2 and Figure 2' is a cross sectional elevation onthe line 2-2 of Figure 1. 'As shown on the drawings a tube a ofcarborundum or like refractory insulating material forms the muflleof'the furnace and is surrounded by a coaxial tube b of similar materialbut of eater diameter and smaller length. Within the annular spacebetween the tubes a and b is arranged a circular series oflongitudinally disposed carbon or graphite rods 0 0 the ends of whichare mounted respectively in two sets of arcuate carbon or graphiteblocks (1 (Z and e 6 (the positions of the blocks c c being shown inbroken lines in Figure 2) secured by means of heat resisting andelectrically insulating cement (not shown) in said annular space andnear the respective ends thereof.

The rods 0 and arcuate blocks d and e are so arranged that an. electriccurrent entering the block al may flow through the rods and blocks insuccession in zig-zag fashion aroundthe series to the return leadconnected with the block d The tubes at and b are retained in positionby meansof two end plates f, g which are held together by longitudinaltie bars h and nuts The end plates 7 and g are centrally apertured so asto fit over the ends of the mufi le tube a whilst the outer tube 7) isclamped between said end plates f and g. The end plate f may beapertured and hushed in any usual mannor for the passage therethrough ofleads such as is adapted to connect the "blocks (1 and d with a sourceof electric energy.

Surrounding the outer tube 6 is a casing m which may be clamped betweenthe end plates 7 and 9 as shown and the annular space between the tube25 and the casing m may be lightly packed with magnesia, kieselguhr orlike non-conductor of heat (not shown) to serve as a lagging.

If desired the mufiie tube a. may be fur ther secured to the end plates7 and g by means of nutsor the like (not shown) in threaded engagementwith the ends of said tube a.

By suitably arranging the size of the rods 0 and their connections withthe arcuate blocks d and c, an electric furnace as hereinbefore setforth may be adapted for operation with an electric current of anydesired voltage.

Having thus described the invention, what is claimed as new is:

1. An electric resistance furnace comprising in combination a mufilechamber, a su rounding chamber shorter in length than said mufiiechamber and a series of conducting rods located bctween said chambers.

2. An lectric resistance furnace comprising in combination a mufflechamber, a surrounding chamber shorter in length than said mufiiechamber, insulating material between said chambers and conducting rodslocated within said insulating material.

3. An electric resistance furnace comprising in combination a chamber ofrefractory material, a series of conducting rods in proximity to saidchamber, and arcuate' blocks'electrically connecting said rods together.i a

4. An electric resistance. furnace comprising in combination a mufiechamber, a surrounding chamber shorter in length than said mulilechamber,'end plates surrounding said mums-chamber in'prcximity to itsends and bearing on the ends of. said surrounding chamber and a seriesof conducting rods located between said chambers.

5. An electric resistance furnace comprising in combination a 'mufiechamber, a surrounding chamber shorter in length than said mufilechamber, end plates surrounding said mufile chamber in proximity to itsends and bearing on the ends of said surrounding chamber, a series ofconducting rods located between said chambers and a casing around saidsurrounding chamber, said casing being packed with heat insulating materal. I

6. An electric resistance furnace. comprising in combination a mufiechamber, a surrounding chamber shorter in length than said munle chamberand a series of conducting rods located between said chambers andelectrically connected together toform an elongated resistance element.

7. An electric resistance furnace comprising in combination a mufllechamber, a surrounding chamber shorter in length than said mufflechamberand a series of conductlessees ing rods located between saidchambers and the end of one rod,,traverse this rod, pass vto theadjacent rod and traverse it from end to end, and likewise eachsuccessive rod.

8. An electric resistance furnace, comprising in combination, amufiechamber, a surrounding chamber shorter in length than said muifiechamber, insulating material between said chambers and in contact withbothof them, and conducting rods located .Within said insulatingmaterial.

9. An electric resistance furnace comprising in combination a mulhechamber, a. surrounding chamber shorter in len'gththan said mufilechamber, insulating material between said chambers and in contact withboth of them, and platessurrounding said mufie chamber in proximity toits ends and bearing on the ends of said surrounding chamber, and aseries of conducting rods located between said chambers.

10. An electric resistance furnace 7 comprising in combination a mufilechamber, a surrounding chamber shorter in length than said mufllechamber, a surrounding chamber shorter in length than said mufilechamber, insulating material between said chambers and in contact withboth of them, and a series of conductin rods located between saidchambers and electrically connected together to form an elongatedresistance ele-' ment.

In testimony whereof we afix our signatures.

LESLIE JOHN HANCOCK.

THOMAS REGINALD HANCOCK.

